A leadscrew is a screw designed to translate a radial motion into a linear motion. Leadscrews when used in a hostile environment such as a sub-sea location tend to erode or become encrusted with matter leading to their unsatisfactory operation.
Leadscrews in which an externally threaded portion is adjustably screwed into a fixed length housing are well known. The housing however does not fully protect the externally threaded portion from the environment over its full range of adjustment.